headroom/tests/test_ccr_response_handler_extra.py
Parideboy 8c8fae0d0b
fix(proxy): reassemble server_tool_use.input from streamed partial_json (#2449)
## Description

Under `--target-ratio 0.4` a session died mid-run with a fatal Anthropic
400:

```
messages.13.content.0.server_tool_use.input: Input should be an object
```

Root cause is not compression of the request: the request path passes
structured blocks through byte-for-byte. It is **SSE stream
reconstruction**. When the proxy rebuilds a full Anthropic message from
the streamed response (non-stream retry, buffered, and CCR round-trip
paths), the `content_block_stop` handler parsed the accumulated
`_partial_json` into `input` only for blocks whose type was exactly
`tool_use`. A `server_tool_use` block streams its input identically via
`input_json_delta`, so its input was never reassembled: the block kept
the empty start-event `input: {}` and leaked the internal
`_partial_json` scratch key. That reconstructed block becomes assistant
history, and on the next turn the client replays it, so Anthropic
rejects `server_tool_use.input`. `--target-ratio` only makes the
buffered/reconstructed path more likely; it does not itself rewrite the
block.

Refs #2438 (Finding 2). Findings 1 (prompt-cache regression) and 3
(compression not engaging) are architectural and tracked separately.

## Type of Change

- [x] Bug fix (non-breaking change that fixes an issue)
- [ ] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [ ] Performance improvement
- [ ] Code refactoring (no functional changes)

## Changes Made

- `headroom/proxy/handlers/streaming.py` (`_parse_sse_to_response`):
gate the `content_block_stop` `_partial_json` → `input` parse on the
presence of `_partial_json`, not `type == "tool_use"`, so
`server_tool_use` (and any future tool-ish block) is reassembled. Always
strip the scratch key; `input` is always a parsed object (`{}` on
malformed/empty JSON).
- `headroom/ccr/response_handler.py`
(`StreamingCCRHandler._reconstruct_anthropic_response`): same
stop-handler fix, and relax the `input_json_delta` accumulator that was
likewise gated on `type == "tool_use"` so server_tool_use partial JSON
is accumulated at all.
- Regression tests in `tests/test_sse_thinking_blocks.py` and
`tests/test_ccr_response_handler_extra.py`: a `server_tool_use` whose
input arrives via `input_json_delta` must reconstruct to the parsed
object with no `_partial_json` leak.
- Leave `CHANGELOG.md` untouched, release-please generates it.

## Testing

- [x] Unit tests pass (`python -m pytest
tests/test_sse_thinking_blocks.py
tests/test_ccr_response_handler_extra.py -q`)
- [x] Linting passes (`ruff check`, `ruff format --check` on the four
changed files)
- [x] Type checking passes (`mypy headroom/proxy/handlers/streaming.py
headroom/ccr/response_handler.py --ignore-missing-imports`)
- [x] New tests added for new functionality

### Test Output

```text
$ python -m pytest tests/test_sse_thinking_blocks.py tests/test_ccr_response_handler_extra.py -q
26 passed in 3.36s

$ ruff check <changed files>
All checks passed!
```

## Real Behavior Proof

- Environment: Windows 11, Python 3.13, local dev checkout on a branch
off upstream/main
- Exact command / steps: Fed a synthetic Anthropic SSE stream with a
`server_tool_use` block whose `input` arrives as `input_json_delta`
partial JSON through both reconstructors (`_parse_sse_to_response`,
`_reconstruct_anthropic_response`); then temporarily restored the `type
== "tool_use"` guard and re-ran.
- Observed result: With the fix, the reconstructed block has `input ==
{"query": ...}` and no `_partial_json` key. With the old guard the test
fails, `input` stays `{}` and the scratch key leaks, reproducing the
malformed block that Anthropic rejects on replay.
- Not tested: End-to-end multi-turn `--target-ratio` session against the
live Anthropic API from this environment, reproduced at the
reconstruction seam instead; the reporter observed the 400 on real
traffic.

## Review Readiness

- [x] I have performed a self-review
- [x] This PR is ready for human review

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-20 11:04:16 -07:00

460 lines
17 KiB
Python

from __future__ import annotations
import json
from typing import Any
import pytest
from headroom.ccr.response_handler import (
CCRResponseHandler,
CCRToolCall,
CCRToolResult,
StreamingCCRBuffer,
StreamingCCRHandler,
)
from headroom.ccr.tool_injection import CCR_TOOL_NAME
class FakeStore:
def __init__(self, *, retrieve_error: Exception | None = None) -> None:
self.retrieve_error = retrieve_error
def retrieve(self, hash_key: str):
if self.retrieve_error:
raise self.retrieve_error
return {"unexpected": True}
async def _async_iter(items: list[bytes]):
for item in items:
yield item
def _sse_json_events(chunks: list[bytes]) -> list[dict[str, Any]]:
events = []
for chunk in chunks:
for line in chunk.decode("utf-8").splitlines():
if not line.startswith("data: "):
continue
payload = line[len("data: ") :]
if payload == "[DONE]":
continue
events.append(json.loads(payload))
return events
def test_extract_tool_calls_google_and_invalid_shapes() -> None:
handler = CCRResponseHandler()
google_response = {
"candidates": [
{
"content": {
"parts": [
{"text": "hello"},
{"functionCall": {"name": CCR_TOOL_NAME, "args": {"hash": "abc"}}},
]
}
}
]
}
assert handler._extract_tool_calls(google_response, "google") == [
{"functionCall": {"name": CCR_TOOL_NAME, "args": {"hash": "abc"}}}
]
assert handler._extract_tool_calls({"content": "bad"}, "anthropic") == []
with pytest.raises(IndexError):
handler._extract_tool_calls({"choices": []}, "openai")
assert handler._extract_tool_calls({"candidates": []}, "google") == []
def test_parse_ccr_tool_calls_google_and_other_calls() -> None:
handler = CCRResponseHandler()
response = {
"candidates": [
{
"content": {
"parts": [
{
"functionCall": {
"name": CCR_TOOL_NAME,
"args": {
"hash": "aaaaaaaaaaaaaaaaaaaaaaaa",
"query": "pizza",
},
}
},
{"functionCall": {"name": "other_tool", "args": {}}},
]
}
}
]
}
ccr_calls, other_calls = handler._parse_ccr_tool_calls(response, "google")
assert ccr_calls == [
CCRToolCall(
tool_call_id=CCR_TOOL_NAME,
hash_key="aaaaaaaaaaaaaaaaaaaaaaaa",
)
]
assert other_calls == [{"functionCall": {"name": "other_tool", "args": {}}}]
def test_execute_retrieval_error_paths(monkeypatch: pytest.MonkeyPatch) -> None:
handler = CCRResponseHandler()
# Retrieval is by hash only; a store error surfaces as a failed result.
monkeypatch.setattr(
"headroom.ccr.response_handler.get_compression_store",
lambda: FakeStore(retrieve_error=RuntimeError("retrieve boom")),
)
retrieve_result = handler._execute_retrieval(CCRToolCall(tool_call_id="t2", hash_key="abc"))
assert retrieve_result.success is False
assert "Retrieval failed: retrieve boom" in retrieve_result.content
def test_create_tool_result_message_google_and_generic_formats() -> None:
handler = CCRResponseHandler()
results = [
CCRToolResult(tool_call_id="headroom_retrieve", content='{"count": 1}', success=True)
]
google_message = handler._create_tool_result_message(results, "google")
assert google_message == {
"role": "user",
"parts": [{"functionResponse": {"name": "headroom_retrieve", "response": {"count": 1}}}],
}
generic_message = handler._create_tool_result_message(
[CCRToolResult(tool_call_id="tool-1", content="not-json", success=False)],
"other",
)
assert generic_message["role"] == "tool"
assert json.loads(generic_message["content"]) == [
{"tool_call_id": "tool-1", "result": "not-json"}
]
invalid_google = handler._create_tool_result_message(
[CCRToolResult(tool_call_id="headroom_retrieve", content="not-json", success=True)],
"google",
)
assert invalid_google["parts"][0]["functionResponse"]["response"] == {"content": "not-json"}
def test_extract_assistant_message_google_and_generic() -> None:
handler = CCRResponseHandler()
google_message = handler._extract_assistant_message(
{"candidates": [{"content": {"parts": [{"text": "hello"}]}}]},
"google",
)
assert google_message == {"role": "model", "parts": [{"text": "hello"}]}
assert handler._extract_assistant_message({}, "google") == {"role": "model", "parts": []}
assert handler._extract_assistant_message({"content": "plain"}, "other") == {
"role": "assistant",
"content": "plain",
}
@pytest.mark.asyncio
async def test_handle_response_openai_success_and_failure(monkeypatch: pytest.MonkeyPatch) -> None:
handler = CCRResponseHandler()
initial_response = {
"choices": [
{
"message": {
"role": "assistant",
"content": None,
"tool_calls": [
{
"id": "call_1",
"type": "function",
"function": {
"name": CCR_TOOL_NAME,
"arguments": '{"hash":"aaaaaaaaaaaaaaaaaaaaaaaa"}',
},
}
],
}
}
]
}
monkeypatch.setattr(
handler,
"_execute_retrieval",
lambda call: CCRToolResult(
tool_call_id=call.tool_call_id,
content='{"hash":"aaaaaaaaaaaaaaaaaaaaaaaa"}',
success=True,
),
)
captured_messages: list[list[dict[str, Any]]] = []
async def success_api_call(messages, tools):
captured_messages.append(messages)
return {"choices": [{"message": {"role": "assistant", "content": "done"}}]}
result = await handler.handle_response(
initial_response, [{"role": "user", "content": "hi"}], [], success_api_call, "openai"
)
assert result == {"choices": [{"message": {"role": "assistant", "content": "done"}}]}
assert captured_messages[0][1]["role"] == "assistant"
assert captured_messages[0][2]["role"] == "tool"
assert handler.get_stats()["total_retrievals"] == 1
async def failing_api_call(messages, tools):
raise RuntimeError("continuation failed")
failed = await handler.handle_response(initial_response, [], [], failing_api_call, "openai")
assert failed == initial_response
def test_streaming_buffer_and_parse_sse_helpers() -> None:
buffer = StreamingCCRBuffer()
assert buffer.add_chunk(b"plain") is False
assert buffer.get_accumulated() == b"plain"
handler = StreamingCCRHandler(CCRResponseHandler(), provider="anthropic")
# Per SSE spec each event is terminated by `\n\n`. The byte-buffer
# parser introduced in PR-A8 requires the spec terminator so partial
# multi-byte UTF-8 reads don't corrupt event boundaries.
stop_details = {"type": "refusal", "message": "policy refusal"}
anthropic_data = b"\n\n".join(
[
b'data: {"type":"message_start","message":{"id":"msg_1","model":"claude-fable-5","role":"assistant","usage":{"input_tokens":7}}}',
b'data: {"type":"content_block_start","index":0,"content_block":{"type":"thinking","thinking":""}}',
b'data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":""}}',
b'data: {"type":"content_block_delta","index":0,"delta":{"type":"signature_delta","signature":"sig_fable"}}',
b'data: {"type":"content_block_stop","index":0}',
b'data: {"type":"content_block_start","index":1,"content_block":{"type":"redacted_thinking","data":"ENC:abc"}}',
b'data: {"type":"content_block_stop","index":1}',
b'data: {"type":"content_block_start","content_block":{"type":"text","text":"Hel"}}',
b'data: {"type":"content_block_delta","delta":{"type":"text_delta","text":"lo"}}',
b'data: {"type":"content_block_stop"}',
b'data: {"type":"content_block_start","content_block":{"type":"tool_use","id":"tool_1","name":"headroom_retrieve"}}',
b'data: {"type":"content_block_delta","delta":{"type":"input_json_delta","partial_json":"{\\"hash\\":\\"abc\\"}"}}',
b'data: {"type":"content_block_stop"}',
(
b'data: {"type":"message_delta","delta":{"stop_reason":"refusal",'
b'"stop_details":{"type":"refusal","message":"policy refusal"}},'
b'"usage":{"output_tokens":3}}'
),
b"data: [DONE]\n\n",
]
)
parsed = handler._parse_sse_stream(anthropic_data)
assert parsed["content"][0] == {
"type": "thinking",
"signature": "sig_fable",
"thinking": "",
}
assert parsed["content"][1] == {"type": "redacted_thinking", "data": "ENC:abc"}
assert parsed["content"][2] == {"type": "text", "text": "Hello"}
assert parsed["content"][3]["name"] == "headroom_retrieve"
assert parsed["content"][3]["input"] == {"hash": "abc"}
assert parsed["stop_reason"] == "refusal"
assert parsed["stop_details"] == stop_details
assert parsed["usage"]["output_tokens"] == 3
openai_handler = StreamingCCRHandler(CCRResponseHandler(), provider="openai")
parsed_openai = openai_handler._reconstruct_openai_response(
[
{"choices": [{"delta": {"content": "Hi"}}]},
{
"choices": [
{
"delta": {
"tool_calls": [
{
"index": 0,
"id": "call_1",
"function": {
"name": "headroom_retrieve",
"arguments": '{"hash":"aaaaaaaaaaaa',
},
}
]
}
}
]
},
{
"choices": [
{
"delta": {
"tool_calls": [
{
"index": 0,
"function": {"arguments": 'aaaaaaaaaaaa"}'},
}
]
}
}
]
},
]
)
message = parsed_openai["choices"][0]["message"]
assert message["content"] == "Hi"
assert message["tool_calls"][0]["id"] == "call_1"
assert message["tool_calls"][0]["function"]["arguments"] == (
'{"hash":"aaaaaaaaaaaaaaaaaaaaaaaa"}'
)
@pytest.mark.asyncio
async def test_streaming_handler_process_stream_pass_through_and_ccr(
monkeypatch: pytest.MonkeyPatch,
) -> None:
response_handler = CCRResponseHandler()
handler = StreamingCCRHandler(response_handler, provider="anthropic")
passthrough_chunks = [
b'data: {"type":"content_block_delta","delta":{"text":"hello"}}',
b'data: {"stop_reason":"end_turn"}',
]
yielded = [
chunk
async for chunk in handler.process_stream(
_async_iter(passthrough_chunks), [], None, lambda m, t: None
)
]
assert yielded == passthrough_chunks
ccr_handler = StreamingCCRHandler(response_handler, provider="anthropic")
monkeypatch.setattr(
ccr_handler,
"_parse_sse_stream",
lambda data: {
"content": [
{
"type": "tool_use",
"id": "tool_1",
"name": CCR_TOOL_NAME,
"input": {"hash": "abc"},
}
]
},
)
async def fake_handle_response(response, messages, tools, api_call_fn, provider): # noqa: ANN001
return {"content": [{"type": "text", "text": "done"}]}
async def fake_response_to_sse(response): # noqa: ANN001
yield b"event: message_start\n"
yield b"event: message_stop\n"
monkeypatch.setattr(response_handler, "handle_response", fake_handle_response)
monkeypatch.setattr(ccr_handler, "_response_to_sse", fake_response_to_sse)
ccr_chunks = [
b'{"type":"tool_use","name":"headroom_retrieve"',
b',"stop_reason":"tool_use"}',
b"tail",
]
streamed = [
chunk
async for chunk in ccr_handler.process_stream(
_async_iter(ccr_chunks), [], None, lambda m, t: None
)
]
assert streamed == [b"event: message_start\n", b"event: message_stop\n"]
@pytest.mark.asyncio
async def test_streaming_handler_falls_back_to_buffer_on_processing_error(
monkeypatch: pytest.MonkeyPatch,
) -> None:
response_handler = CCRResponseHandler()
handler = StreamingCCRHandler(response_handler, provider="openai")
monkeypatch.setattr(
handler,
"_parse_sse_stream",
lambda data: (_ for _ in ()).throw(RuntimeError("parse failed")),
)
chunks = [b'{"type":"tool_use","name":"headroom_retrieve"', b',"stop_reason":"tool_use"}']
streamed = [
chunk
async for chunk in handler.process_stream(_async_iter(chunks), [], None, lambda m, t: None)
]
assert streamed == [b"".join(chunks)]
@pytest.mark.asyncio
async def test_response_to_sse_formats() -> None:
anthropic = StreamingCCRHandler(CCRResponseHandler(), provider="anthropic")
anthropic_chunks = [chunk async for chunk in anthropic._response_to_sse({"content": []})]
assert anthropic_chunks[0].startswith(b"event: message_start\n")
assert anthropic_chunks[-1] == b'event: message_stop\ndata: {"type": "message_stop"}\n\n'
openai = StreamingCCRHandler(CCRResponseHandler(), provider="openai")
openai_chunks = [chunk async for chunk in openai._response_to_sse({"choices": []})]
assert openai_chunks == [b'data: {"choices": []}\n\n', b"data: [DONE]\n\n"]
@pytest.mark.asyncio
async def test_response_to_sse_preserves_anthropic_shape() -> None:
handler = StreamingCCRHandler(CCRResponseHandler(), provider="anthropic")
stop_details = {"type": "refusal", "message": "policy refusal"}
response = {
"id": "msg_1",
"model": "claude-fable-5",
"role": "assistant",
"content": [
{"type": "thinking", "thinking": "", "signature": "sig_fable"},
{"type": "redacted_thinking", "data": "ENC:abc"},
{"type": "text", "text": "done"},
],
"stop_reason": "refusal",
"stop_details": stop_details,
"usage": {"input_tokens": 7, "output_tokens": 3},
}
chunks = [chunk async for chunk in handler._response_to_sse(response)]
events = _sse_json_events(chunks)
message_delta = next(event for event in events if event["type"] == "message_delta")
assert message_delta["delta"]["stop_reason"] == "refusal"
assert message_delta["delta"]["stop_details"] == stop_details
assert any(event.get("delta", {}).get("type") == "signature_delta" for event in events)
assert any(
event.get("content_block", {}).get("type") == "redacted_thinking" for event in events
)
parsed = handler._parse_sse_stream(b"".join(chunks))
assert parsed["content"][0]["signature"] == "sig_fable"
assert parsed["content"][0]["thinking"] == ""
assert parsed["content"][1]["data"] == "ENC:abc"
assert parsed["stop_reason"] == "refusal"
assert parsed["stop_details"] == stop_details
def test_reconstruct_server_tool_use_input_from_partial_json() -> None:
# StreamingCCRHandler._reconstruct_anthropic_response must parse streamed
# input_json_delta into `input` for server_tool_use, not only tool_use.
# The narrow type gate left server_tool_use.input malformed and leaked the
# `_partial_json` scratch key into replayed assistant history → Anthropic
# 400 `server_tool_use.input: Input should be an object` (#2438).
handler = StreamingCCRHandler(CCRResponseHandler(), provider="anthropic")
events = [
{"type": "message_start", "message": {"id": "msg_1", "model": "claude-opus-4"}},
{
"type": "content_block_start",
"index": 0,
"content_block": {
"type": "server_tool_use",
"id": "srvtoolu_1",
"name": "web_search",
"input": {},
},
},
{
"type": "content_block_delta",
"index": 0,
"delta": {"type": "input_json_delta", "partial_json": '{"query": "x"}'},
},
{"type": "content_block_stop", "index": 0},
]
response = handler._reconstruct_anthropic_response(events)
block = response["content"][0]
assert block["type"] == "server_tool_use"
assert block["input"] == {"query": "x"}
assert "_partial_json" not in block